Underreamer.



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VALTER DUNCAN, OF LOS ANGELES, CALIFORNIA, ASSIGNOR OF ONE-HALF TOANTHONY H. HEDLEY, OF SAME PLACE.

UNDEEREAWHER.

SPECIFICATION forrning part of Letters Patent No. 662,895, datedNovember27, 1 900.

Application filed April 4, 1900. Serial No. 11,547. (No model.)

Be it known that I, WALTER DUNCAN, a citizen of the United States,residing at Los Angeles, in the county of Los Angeles and State ofCalifornia, have invented new and useful Improvements in Underreamers,of which the following is a specification.

My invention relates to improvements in reamers for enlarging awell-hole; and the 1o objects of my improvements are, first, to providea reamer that will enlarge the well-hole below the casing whennecessary, and, second, to provide a reamer which will straighten thehole in case the drill gets the hole out of perpendicular. I attainthese objects by the mechanism described herein and illustrated in theaccompanying drawings, forming a part hereof, in whichi Figure l is aside view, partly in section zo and partly in elevation, of my reainer.Fig. 2 is a side View of the same on a plane at right angles to theplane of the view in Fig. l. Fig. 3 is an enlarged longitudinal sectionof the upper part of the reamer-shaft. Fig. 4 is a 2 5 cross-section online 4f 4t of Fig. 3.

A is the shaft or body of my reamer, the.

top of which is screw-threaded, so that it may be easily attachedto thedrill-stem, and in the bottom thereof is a screwthreaded socket 3owhereby any suitable well-boring tool may be attached to the realnerwhen desired. The upper and lower portions of the body are preferablycircular and of a size to snugly t within the casing of the well beingdrilled,

and thereby provide a suitable guide to keep the reanier perpendicular.

In each side of the lower part of the upper circular portion of the bodyare two semi circular grooves B, one on each side thereof,

4o to provide a bearing for the upper ends of cutters O, below which, asshown in Fig. l, the body A is reduced in size for a short distance toprovide clearance for the cutters C when the reamer is passing throughthe casing. The upper ends of the cutters fit into the grooves B. Nearthe upper ends of cutters O are holes D, through which and through holeE in body A and registering therewith when cutters O are in position 5opasses pin F, which, with collar'G, which screws on to body A and passesdown over the upper portion of the cutters, holds the cutters O inposition attached to body A. Pin F has a loose tit in the cutters C anda tight fit in the body A and is kept in position by collar G. In thelower portion of cutters O and on the inner side thereof are sockets Hfor the reception of spiral spring I, which is seated therein and whichpasses through hole J in body A and keeps the cutters ex- 6o panded whenunderreaining. It will be seen that when underreamiug there is somelittle space-K between the lower edge of the cutters O and body A andthat this space decreases until it practically runs out at the groovesB. This space under collar G might pack with debris if there were noupper outlet to the same. As drilling is always done with water in thehole, I provide channels L, which pass out of body A above collar G and7oV furnish an outlet for the upper portion of space K, so that thedebris may freely pass therethrough, and thereby avoid packing space K.

Around the lower edge of cutters O is a concave chamfer O of such depththat when the cutters are pressed in against body A and the tool ispassed down into the casing and the cutters are expanded to contact withthe casing the upper edge of chamferO' will con- 8o tact with thecasing, while the lower or cutting edge thereof will not be in contactwith the casing, thereby permitting the tool t0 slide down to the bottomof the casing, and when the bottom of the casing is passed the cuttersare further expanded by spring H, so that the lower or cutting edge ofthe chamfer O' will contact with the rock or dirt of the well-hole belowthe casing and as the tool is raised and lowered will cut the same until9o the hole is underreamed to the full size of the expansion of cuttersO, which is only re' quired to be a little in excess of the size of thecasing that is being used in the hole in order that it may be pusheddown more easily 9g than if the dirt or rock touched the casing.

Having described my invention, what I claim isl. The herein-describedunderrea1ner,com prising the body A, provided with grooves B, roc one oneach side thereof, and holes E .and .I therethrough, and channels Ltherein; cutters C, one on each side of body A near the top thereof,said cutters having sockets I-I; and holes D therethrough, and chamfersC in the lower outer periphery thereof; spring I adapted to fit in saidsockets and pass through hole J; pin F adapted to pass through holes Din the cutters, and hole E in body A, and collar G adapted to screw onbody A and keep pin F in position, and to keep cutters C from having toogreat expansion.

2. y The herein-described underreamer,comprising a shaft, circular atthe top and bottom and reduced in size intermediate the circularportions, and having holes therethrough and channels therein, as shown;a groove in each side of the bottom of the upper circular portions;cutters having upper circular ends adapted to fit in said grooves; saidcutters having holes extending through the upper ends, and sockets inthe lower ends on the inner` sides, and a chainfer around the outerlower edges thereof; a pin extending through a hole in the shaft andinto the holes in the upper ends of said cutters; a spiral spring eX-tending through a hole in the shaft, and having its ends housed in thesockets in the lower ends of said cutters; and a collar adapted to bescrewed onto the upper circular part of the shaft and to project overthe upper portion of the cutters.

In Witness that I claim the foregoing I have hereunto subscribed mynaine,this 28th day of March, 1900, at Los Angeles, California.

WALTER DUNCAN.

Witnesses:

M. C. WILKINSON, G. E. HARPHAM.

